Chemical process



Patented Aug. 28, 1945 UNITED STATES PATEN'I" orncs CHEMICAL PROCESS Michael Sveda, Cleveland, Ohio, asslgnor to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delawarethe converter gas.

drocarbon.

No Drawing. Application February 17, 1943, Serial No. 476,210

Claims. (Ci. 260 -513) paraflin hydrocarbons. Still further objects will become apparent hereinafter.

The foregoing and other objects of this invention are attained by effecting reaction between sulfur trioxide and a paraiiln with both of the reactants in the vapor phase. As soon as a desired reaction product has been obtained it is withdrawn from the reaction zone and, prefer-- ably, cooled to prevent still further reaction and to prevent the production of undesirable decomposition products. The reaction may further be controlled as set out more fully hereinafter by the use of diluents, by control of the temperature and duration of reaction, and by manipulation of other similar process.

Products of this invention may be made using any paraffin hydrocarbon having at least three carbon atoms. Normally gaseous hydrocarbons such as propane, butane, isobutane, and neo-pentane may very readily be used since no provision need be made for vaporizing these materials. Hydrocarbons which are not gaseous at room temperatures such as iso-pentane, normal butane, normal hexane, iso-hexane, 2,2-dimethyl butane; and 2,8-dimethyl butane, 3-methyl pentane, and higher molecular weight hydrocarbons may be used but they will need to be vaporized before they are brought into contact with sulfur trioxide.

Gaseous sulfur trioxide for use in reactions of the present invention may be obtained from any source and there may be employed, for instance, the pure sulfur trioxide vapor obtained by heating liquid sulfur trioxide or solid sulfur trioxide or that obtained by heating oleum. The sulfur' trioxide-containing mixture of gases obtained from commercial contact converters may similarly be used. If a converter gas is used, care must be exercised to avoid explosive concentrations of hydrocarbons since otherwise an explosion may result from the presence of residual oxygen in To avoid this danger the reaction between thehydrocarbon and the sulfur trioxide may be carried out at a rate in excess of the velocity of the explosion wave caused by the reaction of the residual oxygen and the hyverter gas may be removed or may be burned with hydrogen or carbon prior to use of the gas mixtures for the purposes of the p esent invention.

The primary products obtained contain sulfonic acid or sulfonic anhydride groups, sulfone groups, and sulfate groups. Compounds containing carbonyl and carboxy groups are also formed to a minor extent. I The products may generally be designated as aliphaticpolyhydroxy sulfonic acids which are at least partly esterified with sul.

fate groups, that is, aliphatic hydrocarbon compounds which contain-$03K and OSO:OH groups. Upon dissolving the products in water, according to preferred practices of the invention, hydrolysis results and there are obtained the free polyhydroxy sulfonic acids. These may be more specifically describedas polyhydroxy polysulfonic acids containing sulfone groups. While reference is made to the acid, it will be under stood that it will frequently be found'desirable to isolate the product in the form of a salt of a suitable metal such as barium, cadmium, or sodium,or of ammonia'or a substituted ammonia.

The products of this invention will be found useful as electrolytes and as addition agents for electroplating. The ammonium salts will also be found suitable for use as fiameproofing agents' for the treatment, for instance, of cellulosic articles. They may be used as tanning assistants. Processes of this invention involve, broadly. bringing together a paramn hydrocarbonfand sulfur trioxide with both in the'vapor phase and under conditions which will promote a controlled reaction. After the reaction has continued to a. desired extent the products ,of reaction are withdrawn and the reaction terminated by cooling the product. The conditions of the reaction will ibe more fully discussed under the following headngs: Proportions of reactants two reactants will ordinarily need to be care- Alternatively, the oxygen in the con-,

dinarily desirable to fully regulated depending upon the particular product which it is desired to produce. The amount of sulfur trioxide should ordinarily be substantial and suflicient to insure a maximum yield of the product desired, but it is not oruse an excess of sulfur trioxide since this excess may contaminate the product and may even cause considerable decomposition of the product if it is collected together with unreacted liquid. sulfur trioxide. There is ordinarily no disadvantage in the presence of an excess of paraflin hydrocarbon save as the hydrocarbon contaminates the product. Where products containing relatively high amounts of sulfur are desired it would of course be undesirable to have any considerable excess of hydrocarbon present.

Diluents Temperature reaction The temperature in the reaction zone should be maintained above the boiling point of the sulfur trioxlde and the paramnhydrocarbon to be reacted, though temperatures below the boiling point of sulfur trioxide may be used if diluents are employed. The upper limit of the temperatures employed depends upon such factors as the thermal decomposition point of the hydrocarbon to be reacted, the thermal decomposition point-of sulfur trioxide, and the thermal decomposition point of the product desired. The reaction may be performed at a temperature above the thermal decomposition point of the product to be produced in order to accelerate the reaction but in this event the reaction products should quickly be removed from the reaction zone and cooled before they have a chance to undergo extensive decomposition. Temperature control can readily. be accom-' plished by indirect heat exchange when it isdesired to add or remove heat from the reaction zone, and if it'is desired to initiate the reaction at a comparatively high temperature heat may be added either by separately preheating the reactants to a desired degree or by a pre-v liminary indirect heat exchange of a mixture of the reactants as they pass to the reaction zone.

Generally, low reaction temperatures are conducive to sulfonation while higher temperatures lead to less sulfonation and toe. greater degree of oxidation. I have also observed that higher reaction temperatures lead to some dimerization and sometimes to an even greater degree of polymerization.

Duration of reaction very desirable to remove the product from the reaction zone and cool it. A product formed maysuitably be cooled, for instance, by with be produced which are different from those produced' in a shorter period under otherwise similar conditions. The duration-of reaction thus becomes an important factor in determining the precise character of product. The time of reaction will ordinarily vary from a tenth of a second or so up to a few minutes though in each particular instance the time of reaction can best be determined by a few simple trials.

Pressure Reactions of the present invention may be performed at pressures other than atmospheric to vary the conditions of reaction. Catalysts may be used if desired.

In order that the invention may be better understood reference should be had to the following illustrative examples:

Example I;

Sulfur trioxide and propane were brought together using a reaction tube 16 mm. inside diameter heated for a length of 500 mm. The reaction tube contained a thermocouple leaving an effective heated volume of cc. The reaction conditions were as follows:

Rate of sulfur trioxide flow... 330 cc. per minute Temperature of reaction tube. 300 C. Duration of reaction Approx. V2 second The reaction tube was externally heated to maintain the temperature shown. The gases were passed thru the heated zone and after leaving this zone they were immediately chilled by means of a water-cooled condenser. There was with both a heating means and a cooling means in order to hold the temperatures within the range desired. The conditions of the areaction were as follows:

SO: flow ..e cc./min-.. 1122 Isa-butane flow ....4 --cc./min 745 Isa-butane preheating temperature C 37-52 S0: preheating temperature .30.. 44- 65 Reaction temperature ..C -155 Total 80: input parts by weight 5120 Total iso-butane input. do 2455 Total liquid product formed-- -..do 3101 Total solid product obtained ..do 381 drawing it into a receptacle providedwlth indirect heat exchange. Cooling may, instead, be

effected by running the product into a cold iiuid such as water or aqueous alkaline solutions containing sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, and the The solid and liquid reaction products were separated. The liquid fraction was a dark brown liquid which is thought to be p l hydroxy sulfonic acids which contain sulfate groups. Thi fraction was treated with 6000 parts of ice, and the resulting solution was neutralized with barium carbonate, heated to hydrolyze sulfate groups, and

the above sulfonic acids.

50% by weight of sulfur trioxide as then neutralized again with barium carbonate. After the precipitated barium sulfate was removed, the solution was concentrated and then poured into cold methanol to precipitate a barium salt. I

By analysis, this product was found to be a mixture of the barium salts of the following polyhy droxy sulfonic acids:

82% CsH eOnS:

18% cahoots, Both chemical tests and infra-red spectra have substantiated the presence of hydroxy groups. in

and

This barium saltwas extremely soluble in water,- concentrated sulfuric acid, and polyhydroxylated solvents such as ethylene glycol, propene glycol, and glycerol. and was either slightly soluble or insoluble in the other organic solvents including monohydroxy alcohols.

The solid reaction product was insoluble in cold water, but dissolved in cold dilute alkali, cold aqueous ammonia, and in boiling water. This solid contained a very high proportion of sulfur and-oxygen; carbon, sulfur, and oxygen being present in gram-atomic ratios of 40:38:130. Upon acidic hydrolysis, the product liberated sulfuric acid, indicating a high degree of sulfation oi the product by the sulfur trioxide. After the solid material was hydrolyzed in acid solution, treatment with barium carbonate led to a barium salt having the following empirical composition:

CaHzzSzOxaBa This barium salt was similar in solubilities and other properties to the polyhydroxy sulfonic acids obtained from the liquid product.

Example III Iso-butane was used in a process like that of Example II but with different reaction conditions as shown below. The reaction products were coloed by means of an ice-water condenser and then immediately passed into an aqueous suspension of barium carbonate. The conditions used in this experiment were as follows:

SO: flow ..cc./min 226 Iso-butane flow do 2040 S03 preheating temperature -C..- 55 Iso-butane preheating temperature.. C 47-48 Reaction temperature C 60-75 Total input parts by weight 2&8 Total iso-butane input do 1810 27% C4H1oSOo 73% C4H10S20a Example IV A process like that of Example I was carried out using n-butane instead of propane. The n-butane was not as reactive as iso-butane, but

" preheating temperathereactlon were as follows:

use n-Butane preheating terns perature a 158-163 C. Reaction temperature (heat supplied)-.. C.

now-.. 1142 cc. per min. Total 50: input 2838 parts by wt. 80: passingthmush unreacted 592 parts by wt.

- i 4 (20.8 of input) 80: converted to 802 by reaction 490 parts by wt. (17.3% of input) 803 combined with I n-butane 1756 parts by wt.

. (61.9% of input) n-Butane flow 745 cc. per minute Total n-butane input-"i- 1285 parts by wt. n-Butane reacting with 80: 655 parts by wt.

(43.2% of input) Total liquid product formed 2311 parts by weight (1758 parts coming from S0: and 555 parts coming from n-butane) Total water-soluble barium salt isolated 350 parts Only a liquid reaction product was formed with n-butane, in contrast to the iso-butane, where both liquid and solid reaction products were obtained. The liquid formed in the n-butane-sulfur trioxide reaction contained sulfonic acid groups, sulfate groups, and minor quantities of carboxy and carbonyl groups. The product was treated with three times its weight of ice and the resulting solution was heated to hydrolyze sulfate groups. After neutralization and removal of the barium sulfate, the solution was cooled to crystallize out minor quantities of barium methane disulfonate, leaving a solution of a very water-soluble barium salt.

Analytical data on the latter showed that this product contained barium salts of the following acids:

31% Oil-Iss0: and

While numerous illustrative processes and compositions have been shown, it will be understood that without departing from the spirit of this invention one skilled in the art may readily device numerous processes for effecting the vapor phase reaction of paraflin hydrocarbons with sulfur trioxide and to produce numerous novel products.

I claim:

1. In a process for the reaction of a paraflin hydrocarbon with sulfur triomde, the step comprising reacting a paraflin hydrocarbon having at least three carbon atoms with sulfur trioxide in the vapor phase.

2. In a processi'or the reaction of a paraflin hydrocarbon with sulfur trioxide, the step comprising reacting isobutane with sulfur trioxide in the vapor phase.

3. In a process for the reaction of a paraflin hydrocarbon with sulfur trioxide, the step comprising reacting n-butane with sulfur trioxide in the vapo phase.

4. In a process for the reaction of a paraflin hydrocarbon with sulfur trioxide, the step comprising reacting propane with sulfur trioxide in the vapor phase.

5. In a process for the reaction of a paramn hydrocarbon with sulfur trioxide, the step; comprising leading a vaporized parainn hydrocarbon having at least three carbon atoms and vaporized sulfur tioxide into a reaction zone, effecting reaction, and withdrawing a reaction product from the reaction zone.

6. In a process for the reaction of a paraflin hydrocarbon with sulfur trioxide, the steps comprising leading a vaporized paramn hydrocarbon having at least three carbon atoms and vaporized sulfur trioxide into a reaction zone, eifecting reaction withdrawinz a reaction product from the reaction zone,,.and hvdrolyzing the product;

7. An aliphatic polyhydroxy eulfonic acid containing suifone groups. the product being obtained by hydrolyzing the product of the vapor reaction of 'a paraflin hydrocarbon with sulfurtrioxide.

8. An aliphatic polyhydroxy suifonic acid containing sulfone groups, the product beinz obtained by hydrolyzing the product of the vapor phase reaction of isobutane with sulfur trioxide. 9. An aliphatic mlyhydroxy sulfonic acid containing sulfone groups, the product being obtained by hydrolyzing the product of the vapor phase reaction of n-butane with sulfur trioxide.

10. An aliphatic polvhydroxy sulfonic acid containing sulfone groups, the product being obtained by hydrolyzing the product of the vapor phase reaction of propane with sulfur trioxide.

p MICHAEL BVEDA, 

